The present disclosure relates to a method and an apparatus for mounting an electric component such as a semi-conductor chip on a wiring board. More particularly, the present disclosure relates to a method and an apparatus for mounting an electric component using an adhesive agent.
A variety of electronic devices are expected to be smaller or thinner in size as the electronic devices including mobile phones have been rapidly widespread in recent years. A variety of electronic components such as a large scale integration (LSI) chip and the like need to be densely mounted on a wiring board to meet such a recent demand for the smaller or thinner electronic devices.
Accordingly, the electronic component tends to be mounted on the wiring board in a state that the electronic component remains as a chip, that is, the electronic component tends to be mounted on the wiring board using a bare chip mounting technique, as a flexible printed wiring board (also referred to as a flexible printed circuit or FPC) has been widespread while a high density mounting has been demanded. Such a method for directly mounting the bare chip on the wiring board is known to use an adhesive agent.
For example, in a case where an anisotropic conductive adhesive film (also referred to as an anisotropic conductive film or ACF) is used for the mounting, the electronic component is placed on the wiring board including the anisotropic conductive adhesive film attached thereto, and then the electronic component is pressurized and heated using a flat hard head made of metal or ceramics and the like, so that the anisotropic conductive adhesive film is hardened by a thermocompression bonding mounting technique.
In such a case of mounting the electronic component by application of the pressure and heat using the hard head, however, sufficient heat may not be applied with respect to a fillet portion of the adhesive agent in the vicinity of the electronic component during the thermocompression bonding, causing deterioration of connection reliability. Moreover, a plurality of electronic components are difficult to be mounted.
Accordingly, a technique (e.g., Patent Document 1) has been proposed in recent years to enhance the connection reliability by applying uniform pressure on a pressure surface of the electronic component by performing the thermocompression bonding of the electronic component using a fat elastic head made of an elastic body such as silicone rubber. Patent Document 1 discloses the deterioration of the connection reliability and initial resistance of the adhesive agent due to application of insufficient pressure with respect to the electronic component where the elastic member is made of elastomer having rubber hardness below 40, and the deterioration of the connection reliability due to generation of voids in binding resin of the adhesive agent caused by application of insufficient pressure with respect to the fillet portion where the elastic member made of the elastomer has a rubber hardness greater than or equal to 80. In a case of mounting the electronic component using the elastic head, therefore, the elastic head preferably a rubber hardness between 40 and 80.    Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-32952.
In addition, the electronic components to be mounted have tended to be thin in recent years as the electronic devices are expected to be smaller or thinner in size or lighter in weight.
The usage of the elastic head having the preferred rubber hardness disclosed in Patent Document 1 causes an influence on the connection reliability due to a significant increase in a warpage amount of a thin electronic component warped subsequent to the thermocompression bonding in a case where the thin electronic component is mounted using a conductive adhesive agent such as an anisotropic conductive adhesive film having a low melt viscosity.